Although there are various types of rotary pumps, the most common on pipeline services are two- and three-screw pumps, gear pumps (internal and external), and vane pumps for low pressure services. The rotary, positive displacement pumps are often used when products such as heavy crude oil, bunker fuels, low sulfur fuels, asphalt, Orimulsion ®, and similar products are transported. Pipelines handling liquids in excess of about 500 SSU viscosity normally use rotary, positive displacement pumps both for optimum efficiency and lower initial cost. Initial and future conditions should be evaluated so that pumps with sufficient flexibility to handle both conditions with minor changes may be selected. The first step in selecting centrifugal pumps is to analyze the pipeline system and determine its characteristics such as the pressure required to move the desired flow rate. The selection of the proper pump depends on the system throughput, viscosity, specific gravity, and head requirements for a particular application.
Centrifugal pumps are best suited for large volume applications or for smaller volumes when the ratio of volume to pressure is high. This chapter focuses on the various pumps used in pipeline industry.
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